Long-term clinical efficacy in grass pollen–induced rhinoconjunctivitis after treatment with SQ-standardized grass allergy immunotherapy tablet

Background Sustained and disease-modifying effects of sublingual immunotherapy have never before been confirmed in a large-scale randomized, double-blind, placebo-controlled trial. Objective We sought to investigate sustained efficacy 1 year after a 3-year period of daily treatment with the SQ-standardized grass allergy immunotherapy tablet Grazax ( Phleum pratense 75,000 SQ-T/2,800 BAU; ALK-Abelló, Hørsholm, Denmark). Methods A randomized, double-blind, placebo-controlled, phase III trial including adults with a history of moderate-to-severe grass pollen induced rhinoconjunctivitis inadequately controlled by symptomatic medications. The analysis set comprised 257 subjects at the follow-up. Efficacy end points were rhinoconjunctivitis symptom and medication scores, quality of life, and percentages of symptom and medication free days. Immunologic end points included grass pollen–specific serum IgG4 and IgE-blocking factor. Safety was assessed based on adverse events. Results Significant improvements in efficacy were consistently shown during 3 years' treatment. One year after treatment, the active group showed sustained reductions in mean rhinoconjunctivitis symptom scores (26%, P < .001) and medication scores (29%, P = .022) when compared with placebo. This level was similar to the efficacy observed during the 3-year treatment period. The differences in percentages of symptom- and medication-free days were significant during and 1 year after treatment. The active group also reported sustained and significant improvements in quality of life. Sustained clinical benefit was accompanied by immunologic changes. No safety issues were identified. Conclusion Three years of treatment with the SQ-standardized grass allergy immunotherapy tablet resulted in consistent clinical improvement and accompanying immunologic changes that were sustained 1 year after treatment, which is indicative of disease modification and associated long-term benefits.